Do you need to hold your urine when doing NT?

The NT test can examine the thickness of the skin behind the baby's neck through B-ultrasound, and thus determine the possibility of the baby suffering from Down syndrome, so all expectant mothers must pay attention to it. So what are some common problems? Do I need to hold my urine when doing a NT test?

Do I need to hold my urine for the NT test?

NT (nuchal translucency scanner) examination is a B-ultrasound examination item. It does not require blood tests. Expectant mothers do not need special preparation for the NT examination. Eating and drinking water will not affect the test results, so they can eat breakfast. Since it is an abdominal color ultrasound examination, there is no need to hold urine.

However, if the baby does not cooperate and the injury is not good, it cannot be seen. The doctor will usually ask the expectant mother to go out for a walk before going home. Sometimes the doctor will continue to press the pregnant mother's belly very hard. Don't be afraid. This is usually because the baby is asleep and in a bad position. The doctor will wake him up and ask him to turn over. The whole test takes about 10-20 minutes, and it may be shorter if the baby cooperates well. Therefore, the only thing that expectant mothers should pay attention to before doing the NT test is to maintain a good mood and learn to talk to the baby more. Although the baby is not big at this time, the baby can still feel the mother's love.

Because the fetus is too small to observe the nuchal translucency before 11 weeks of pregnancy, and the fetus gradually grows after 14 weeks of pregnancy, it may absorb unnecessary blood from the nuchal translucency and affect the test results. Therefore, it is best for pregnant women to do NT within 11-14 weeks of pregnancy to avoid inaccurate test results.

In addition, it is best to book the NT test in advance. Generally, you can start making an appointment with the hospital 11 weeks before pregnancy to facilitate the schedule. Do not make a reservation after 13 weeks of pregnancy to avoid long queues. Doing NT beyond the gestational age will affect the success rate of the test results.

How to do NT test

Transvaginal color Doppler ultrasound examination is performed on pregnant women at 11-14 weeks of gestation to accurately measure the thickness of the fetal nuchal translucency.

1. During the color Doppler ultrasound examination, the fetus's brachiocephalic diameter (CRL) and biparietal diameter are first measured to determine the ultrasound gestational age. Then the fetal structure is checked in sequence, and some important indicators are observed, such as fetal heartbeat, fetal movement, the connection position of the umbilical cord and the fetus, the growth and development of the fetal limbs, the choroid plexus in the brain, etc., as well as fetal abnormalities such as holoprosencephaly, choroid plexus cyst, umbilical hernia, and other growth and development abnormalities.

2. The thickness of the nuchal translucency is measured in the short-axis sagittal cross-section of the fetus, and the fetal head and spine are in a straight line during the measurement. Adjust the magnification so that the fetus' body occupies about 3/4 of the screen size. The measuring points were placed at the inner edges of two high-echo lines for measurement. The two high-echo lines represent the skin echo and the spinal surface soft tissue echo, respectively. The middle part is the nuchal translucency.

3. Take a short-axis sagittal cross-section of the fetus, with the embryo in a naturally flexed position, and accurately measure the thickest position of the echo-free transparent layer of the subcutaneous tissue in the fetus's neck, from the inner edge of the skin layer to the edge of the subcutaneous tissue. Measure accurately three times and take the thickest value.

4. If the thickness of the fetal nuchal translucency is measured to be ≥3mm (or ≥2.5mm and the gestational age calculated based on the fetal head arm diameter is <12 weeks), the pregnant woman is recommended to undergo amniocentesis or chorionic villus sampling for fetal chromosome karyotype analysis.